Abstract

Inclusive jet and dijet cross sections have been measured in proton-proton collisions at a centre-of-mass energy of 7 TeV using the ATLAS detector at the Large Hadron Collider. The cross sections were measured using jets clustered with the anti-kT algorithm with parameters R=0.4 and R=0.6. These measurements are based on the 2010 data sample, consisting of a total integrated luminosity of 37 inverse picobarns. Inclusive jet double-differential cross sections are presented as a function of jet transverse momentum, in bins of jet rapidity. Dijet double-differential cross sections are studied as a function of the dijet invariant mass, in bins of half the rapidity separation of the two leading jets. The measurements are performed in the jet rapidity range |y|<4.4, covering jet transverse momenta from 20 GeV to 1.5 TeV and dijet invariant masses from 70 GeV to 5 TeV. The data are compared to expectations based on next-to-leading order QCD calculations corrected for non-perturbative effects, as well as to next-to-leading order Monte Carlo predictions. In addition to a test of the theory in a new kinematic regime, the data also provide sensitivity to parton distribution functions in a region where they are currently not well-constrained.

Highlights

  • At the Large Hadron Collider (LHC), jet production is the dominant high transverse-momentum process

  • The inclusive jet double-differential cross section is shown in Figs. 9 and 10 and Tables V–XVIII in Appendix B for jets reconstructed with the anti-kt algorithm with R 1⁄4 0:4 and R 1⁄4 0:6

  • Cross section measurements have been presented for inclusive jets and dijets reconstructed with the anti-kt algorithm using two values of the clustering parameter (R 1⁄4 0:4 and R 1⁄4 0:6)

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Summary

INTRODUCTION

At the Large Hadron Collider (LHC), jet production is the dominant high transverse-momentum (pT) process. The analysis presented here extends the previous measurement using the 2010 data sample of ð37:3 Æ 1:2Þ pbÀ1, an integrated luminosity more than 2000 times larger than that of the previous study This more than doubles the kinematic reach at high jet transverse momentum and large dijet invariant mass. This data sample extends the existing inclusive jet pT measurement from 700 GeV to 1.5 TeV and the existing dijet mass measurement from 1.8 TeV to 5 TeV. This analysis probes next-to-leading-order (NLO) perturbative QCD (pQCD) and parton distribution functions (PDFs) in a new kinematic regime. The results span approximately 7 Â 10À5 < x < 0:9 in x, the fraction of the proton momentum carried by each of the partons involved in the hard interaction

THE ATLAS DETECTOR
CROSS SECTION DEFINITION
MONTE CARLO SAMPLES
NLO predictions
Nonperturbative corrections
NLO Matrix Element þ Parton Shower
Data set
Trigger
Jet reconstruction and calibration
Uncertainties in jet calibration
Event selection
Jet selection
Luminosity
UNFOLDING
Cross-check with jet shapes
Ár prT pRT
Uncertainty sources from jet reconstruction and calibration
Uncertainty propagation
Summary of the magnitude of the systematic uncertainties
Correlations
Inclusive jet cross sections
Dijet cross sections
CONCLUSIONS
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